The invention is generally directed to transparencies, and more specifically, the present invention is directed to typewriter transparencies with specific coating compositions. Thus, in one embodiment the present invention relates to coatings for transparencies for use with single strike ribbons, correctable ribbons, multistrike ribbons, and fabric ribbons. In one specific embodiment of the present invention there are provided as coatings blends of poly(vinyl methyl ether), and poly(styrene) present on various known polymer substrates including Mylar.
Four types of ribbons known for use in conventional typewriters are fabric based, single strike, multistrike, and correctable. Fabric based ribbons consist of a fabric, such as nylon, polyester or silk doped with mineral or vegetable oil based dyes. An example of a single strike ribbon is Mylar which is coated with a blend of carnauba, bees and paraffin waxes, carbon black pigment and oil. In multistrike ribbons, the inks selected are comprised of blends of carbon black with rape seed oil, Reflex blue pigment and lecithin. Correctable ribbons are usually composed of Mylar coated with a blend of soluble nylon, carbon black and low percent mineral oil. Also, it is known that coatings developed for single strike and correctable ribbons may not be suitable for multistrike and fabric based ribbons.
Transparencies, including typewriter ribbon transparencies, are also known. Related prior art includes U.S. Pat. Nos. 3,002,858; 4,379,804; 4,461,793; 4,474,850; 4,503,111; 3,790,435; 4,233,354; and 4,301,195. There is illustrated in the U.S. Pat. No. 4,301,195 patent a transparent sheet material comprised of a transparent backing having an ink receptive stratum thereon containing, for example, a mixture of two polymers, or individual layers of each polymer. One of the polymers selected is obtained by the reaction of an epoxidized water insoluble neutral rubbery polymer and a water soluble secondary monoamine, reference the abstract of the disclosure. In the '358 patent, there is illustrated an ink receptive coating composition capable of receiving a typewritten image, wherein there can be selected as a coating ethyl cellulose, and a substrate such as Mylar. Reference to column 1, line 12, of this patent indicates that the plastics referred to upon which is intended to present images include transparent, translucent, or opaque sheets, and laminated structures. Also, in the aforementioned '354 patent, there is illustrated printed polyester films with certain properties; and containing on its surface a well adhering printed layer formed by a printing ink with a cellulose derivative as a binder. In the '453 patent, there is described synthetic writing paper comprised of a Mylar base, and a coating thereover including poly(styrene).
Other transparencies similar to those illustrated in the U.S. Pat. No. 4,301,195 patent are disclosed in U.S. Pat. Nos. 4,474,850, and 4,503,111. Furthermore, there is disclosed in U.S. Pat. No. 4,461,793 coatings that can be applied to a heat shrinkable base material which is capable of forming a printing layer thereon. Specifically, reference column 2, line 1, of this patent there is illustrated a printable coating useful for application to heat shrinkable identification devices containing a polyester film, calcium carbonate, and a silicate compound. Apparently, the fiber of the '793 patent is useful as a receiver for typewritten images.
There is also illustrated in a copending application U.S. Ser. No. 695,026, Jan. 25, 1985, now U.S. Pat. No. 4,592,954, entitled Ink Jet Transparencies With Coating Compositions Thereover, the disclosure of which is totally incorporated herein by reference, a transparency for ink jet printing comprised of a supporting substrate; and thereover a coating of a blend of carboxymethyl cellulose, and poly(ethylene oxide). Prior art illustrated in the aforementioned copending application as filed, which may be of interest with respect to the invention of the present application, includes U.S. Pat. Nos. 4,273,602; 4,370,379; and 4,234,644. Disclosed in the '602 patent are heat sensitive recording materials comprised of a support sheet of a thickness of from 5 to 40 microns containing thereon a heat sensitive transfer layer with a phenolic material, a colorless or precolored component which reacts with the phenolic to form a color upon application of heat, and a heat fusible material with a melting point of 40 to 150 degrees Centigrade. It is indicated in this patent that heat sensitive transfer layers can be formed from waxes, or resins of a low molecular weight with colored dyes dispersed therein; however, apparently there are problems associated with such a method in that part of the layer transfers to ordinary paper causing undesirable staining and a decrease in contrast between the letters and the background. Accordingly, the recorded letters cannot be easily read.
Also known is the preparation of transparencies by electrostatic means, reference U.S. Pat. No. 4,370,379, wherein there is described the transferring of a toner image to a polyester film containing, for example, a substrate and a biaxially stretched poly(ethylene terephthalate) film, including Mylar. Moreover, in U.S. Pat. No. 4,234,644 there is disclosed a composite lamination film for electrophoretically toned images deposited on a plastic dielectric receptor sheet comprising in combination an optically transparent flexible support layer, and an optically transparent flexible intermediate layer of a heat softenable film applied to one side of the support; and wherein the intermediate layer possesses good adhesion to the support.
Although the above mentioned transparencies are suitable for their intended purposes, there remains a need for new transparencies. Particularly, there remains a need for typewriter transparencies useful with multistrike ribbons and fabric ribbons, and wherein the coatings selected are compatible with these ribbons. Also, images obtained on materials such as the prior art poly(styrenes) with single strike or correctable ribbons require long fixing times, and are not smudge proof, problems overcome with the transparencies of the present invention.